Lower value notes were intended to compensate for the chronic shortage of coinage which resulted from the Napoleonic Wars. According to PMI, 'silver notes' were defined in an Act of 1799 as notes for 9 shillings, 6 shillings and 3 shillings 9 and half pence. The last one equates to 1/6th of a British Guinea. The non-equivalence of the Irish and British pounds lead to odd denominations in Irish currency.